1. Field of the Invention
The present invention relates generally to band saws installed on band saw apparatuses to be used in lumber processing, and more particularly to a band saw which is novel in construction and capable of eliminating or minimizing occurrence of sawing bends (deemed herein to include cutting bends) due to cutting resistance or friction generated between the saw band and a lumber.
2. Description of the Related Art
As is well known in the art, a band saw used for cutting lumber and the like has a construction wherein multiple saw teeth are formed on the edge portion of a continuous annular plate. By suspending the band saw around a pair of saw wheels mounted on a band saw apparatus and causing it to revolve in the circumferential direction based on the driving of such saw wheels, the lumber or the like is sawed. When a conventional band saw is used continuously, the saw teeth undergo heat deformation or heat buckling due to cutting resistance or friction against the saw teeth, thereby causing the desired cutting precision and cutting efficiency to be lost and giving rise to the problem of so-called sawing bend. In addition, stress due to cutting resistance against the saw teeth tends to become concentrated at the saw tooth bases, causing cracking.
To cope with these problems, it has been conceived to coat certain areas of the saw teeth, saw tooth bases and the like with a hard material at prescribed locations, as described in JP-A-1-188221 or JP-U-7-45012, for example, thereby increasing the rigidity of the saw teeth and saw tooth bases However, in the band saw described in the above documents, the process of coating the saw teeth, saw tooth bases and the like with a hard material is troublesome and expensive. Further, since stress then becomes concentrated at the borders between the coated areas and the non-coated areas, the problems of deformation and cracking prone to occur at these border areas as a result of metal fatigue and the like.
In order to reduce the concentration of stress at the saw tooth bases, it has been proposed to subject the saw tooth bases to round edge processing, as described in JP-U-47-4717, or to slant each gullet (which shall herein be deemed to include the tooth base) at an angle from a prescribed point from the outer side of the saw along the saw's thickness, as described in JP-A-09-503166. However, because each saw tooth and saw tooth base of the band saw described in the above document must be individually processed, manufacturing and processing involve a substantial amount of work. Additionally, since it is difficult to maintain the overall strength of the saw due to the smaller volume of each saw tooth near the saw tooth base, neither of these processing operations is necessarily effective in preventing sawing bend due to heat buckling and the like.
In short, in the conventional constructions including those described above, it is difficult to easily and effectively strengthen the saw teeth and saw tooth bases. Accordingly, in order to prevent sawing bend and ensure stable cutting, the band saw must be replaced frequently, resulting in diminished cut lumber production efficiency.